The present invention relates to a steering column assembly for a vehicle such as a motor vehicle. Especially, the present invention relates to a tilt steering column assembly including a tilt lock mechanism, a tilt spring and a mounting bracket usable for fixing the column assembly to a vehicle body.
The steering column assembly, in general, extends obliquely and upwardly from a steering gear, and has a steering wheel at the top. The tilt steering column assembly permits a driver to move the steering wheel up and down to a desired angular position. The tiltable steering column can improve the safety of a vehicle by providing ergonomic driving comfort. In some models the tilt spring is arranged to cause the steering wheel to rise rapidly up from a preset position to an uppermost position immediately after release of the tilt lock so that a wider space is available for the driver to get on or off the car.
In large sized vehicles such as heavy trucks, a tilt hinge is often placed near the driver's foot position. In passenger cars, however, the tilt hinge is usually placed at a higher level near the driver's hands to leave a comfortable space for the legs and knees of the driver.
There have been proposed various tilt lock (or latch) mechanisms. In one example, a lock device is provided only on one side of a movable bracket (Japanese Utility Model Examined Publication No. 57-53730). Another example is a two-sided type having two locks on left and right sides (Japanese Utility Model Provisional Publication No. 1-123969). This type is advantageous for improving the rigidity of the structure and installing an air bag system. A third example is a center lock type (Japanese Utility Model Examined Publication No. 2-34145) in which the lock mechanism is placed under the steering column near the tilt hinge axis.
The two sided type tilt lock mechanism is complicated in construction, heavy in weight, and unfavorable in manufacturing cost. Besides, it is necessary to maintain the correct positional relationship and synchronism between the left and right sides to avoid incomplete engagement. The conventional center lock type mechanism uses engagement between gear teeth formed in a convex cylindrical surface of a swingable gear member. In this center lock mechanism, however, the gear members must be positioned accurately relative to each other to ensure reliable engagement.
Still another examples of the above type of mechanisms are shown in U.S. Pat. No. 3,355,962; Japanese Patent Provisional Publications Nos. H2-92779, and S64-83455, and Utility Model Provisional Publications Nos. S57-53730 and S56-16581.